Back pain, and particularly lower back pain, is a major expense to society and is one of the most common disabling problems of those of working age. Injuries to the back vary from herniated disks of the spine to muscle strains and nerve damage. In the back or posterior end of the human body, the epidural space is potential space located in and extending the length of the spine. The epidural space is defined along one edge or side by the dura mater which surrounds the spinal cord. The epidural space is further defined along a second edge or side by the periosteum of the bony vertebrae or by the ligamentum-flavum at the vertebral interspaces. Along the interior surface of the ligamentum-flavum lies the venus plexus, a complex configuration of veins. The epidural space contains fat, connective tissue, blood vessels, lymphatic vessels, nerve fibers, and other structures. Various lesions, cystical masses, and nerve damage can occur in and around the epidural space which causes various back problems for the human body.
Although applying anesthesia to the epidural space has been known for procedures such as child birth or the like, the anatomy of the epidural space and related structures has not been fully investigated. Conventionally, the insertion of a catheter, fluid introducer, or the like for inducing spinal anesthesia directly into the subarachnoid space of the spinal column, such as seen in U.S. Pat. No. 5,232,442 by Johnson, et al. entitled "Method And Apparatus For Inducing Anesthesia", has been through fluoroscopic or radiographic observation. Fluoroscopic observation techniques have also been used to try to locate the various sources of problems associated with back pain such as seen in U.S. Pat. No. 5,215,105 by Kizelshteyn, et al. entitled "Method Of Treating Epidural Lesions". The fluoroscopic techniques are helpful for general guidance of instruments or other devices, but fail to give the physician or other medical personnel a detailed picture of structures within vessels or cavities, such as the epidural space, and therefore are limited in identifying the source of back pain problems.
Also, endoscopes have been used whereby internal areas or organs within a body vessel or cavity may be observed by inserting an elongated insertable part of the endoscope through a tube or sleeve inserted into a body vessel or cavity, or directly into the body vessel or cavity itself, such as seen in U.S. Pat. No. 5,195,541 by Obenchain entitled "Method Of Performing Laparoscopic Lumbar Discectomy". An endoscope, as used herein, is an instrument for examining the interior of a bodily canal or hollow organ. A catheter, on the other hand, is a tube inserted into a bodily channel, such as a vein, to maintain an opening to a body vessel or cavity. These endoscopes, however, are relatively large with respect to a catheter and, therefore, do not cooperate with a catheter for performing delicate surgery such as the type surrounding the back or spinal column.
Further, fiber optic scopes or fiberscopes have been used for various types of surgery such as surrounding the heart. These fiberscopes often are inserted into a vein or an artery for viewing blockage or the like within the vein or artery. The epidural space, however, has not fully been explored using visual techniques because the epidural space, as described above, does not take the form of a vein or artery. Because the epidural space collapses around an instrument or device inserted therein such as a catheter, an endoscope, a fiberscope, or a cutting tool, the space has not been considered for optical scope viewing or for performing many types of epidural surgical procedures.
Therefore, there is still a need for a method of epidural surgery that allows a physician to effectively enter the epidural space of a patient, visually observe and document a problem area which could be the source of back pain in the patient, and therapeutically treat the problem area in or around the epidural space in a minimal amount of time and with minimal amount of cutting and other potential damage to the patient during surgery.